Injector water intrusion seal with blow out volume

Abstract

A fluid injector includes a housing and an inlet tube having a portion received in the housing. A primary seal creates a seal between surfaces of the housing, the inlet tube, and an inlet of the injector. A groove is in the housing and a secondary seal is in the groove to defining a seal between the housing and a portion of the inlet of the injector. A recessed portion is defined in the housing and is in communication with the groove. The recessed portion defines a blow-out volume such that when the primary seal is leak tested, an indication of a leak of the primary seal can be detected when the pressurized air moves past the primary seal and forces a portion of the secondary seal to an unsealed position into the blow-out volume.

What is claimed is: 
     
       1. A fluid injector comprising:
 a housing; 
 an inlet tube having a portion received in the housing, the inlet tube having an opened end for receiving fluid from an inlet defined by an inlet cup assembly of the injector; 
 a primary seal disposed about a portion of the inlet tube so as to create a seal between surfaces of the housing, the inlet tube, and the inlet cup assembly of the injector; 
 a groove defined in a periphery of the housing; 
 a secondary seal disposed in the groove and defining a seal between the housing and a portion of the inlet cup assembly of the injector; and 
 a recessed portion defined in the housing and in communication with the groove so that due to the recessed portion, an entirety of the secondary seal is not supported by the groove, 
 wherein the recessed portion defines a blow-out volume such that when the primary seal is leak tested by forcing pressurized air through the inlet of the injector, an indication of a leak of the primary seal can be detected when the pressurized air moves past the primary seal and forces a portion of the secondary seal to move to an unsealed position into the blow-out volume. 
 
     
     
       2. The injector of  claim 1 , wherein the recessed portion is substantially U-shaped and extends axially from the groove. 
     
     
       3. The injector of  claim 2 , wherein the recessed portion has a maximum width of about 3.0 mm. 
     
     
       4. The injector of  claim 1 , wherein the groove is generally annular and the secondary seal is an elastomer O-ring. 
     
     
       5. The injector of  claim 1 , wherein the primary seal is an elastomer O-ring. 
     
     
       6. The injector of  claim 1 , wherein the secondary seal is adjacent to the primary seal. 
     
     
       7. The injector of  claim 1 , further comprising a shield connected to the inlet cup assembly and surrounding a portion of the housing. 
     
     
       8. The injector of  claim 1 , wherein the injector is a Reductant Delivery Unit in a Selective Catalytic Reduction system and the primary seal is constructed arranged to seal urea from migrating past the inlet cup assembly and between the housing and the inlet tube and the secondary seal is constructed and arranged to seal liquid from migrating past the inlet cup assembly and between the housing and the inlet tube. 
     
     
       9. The injector of  claim 1 , further comprising a groove in communication with the recessed portion and constructed and arranged to permit air to move around the secondary seal when the secondary seal moves to the unsealed position during leak testing of the primary seal.